linux-kernel - Re: [PATCH] arch: x86: entry: vdso: fix type conversion on printf() call

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Message-ID: <CALCETrWukL-wMnq==-V4dvh_Q+h_sRvJBuTF3jQtHPo4MZ3AQA@mail.gmail.com>
Date:   Tue, 15 Dec 2020 08:15:09 -0800
From:   Andy Lutomirski <luto@...nel.org>
To:     "Enrico Weigelt, metux IT consult" <info@...ux.net>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Andrew Lutomirski <luto@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        X86 ML <x86@...nel.org>, "H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH] arch: x86: entry: vdso: fix type conversion on printf() call

On Tue, Dec 15, 2020 at 8:03 AM Enrico Weigelt, metux IT consult
<info@...ux.net> wrote:
>
> Fixing the following compiler warning by explicit conversion to long:
>
> In file included from /home/nekrad/src/apu2-dev/pkg/kernel.apu2.git/arch/x86/entry/vdso/vdso2c.c:162:0:
> /home/nekrad/src/apu2-dev/pkg/kernel.apu2.git/arch/x86/entry/vdso/vdso2c.h: In function 'extract64':
> /home/nekrad/src/apu2-dev/pkg/kernel.apu2.git/arch/x86/entry/vdso/vdso2c.h:38:52: warning: format '%lu' expects argument of type 'long unsigned int', but argument 4 has type 'size_t {aka unsigned int}' [-Wformat=]
>   fprintf(outfile, "static const unsigned char %s[%lu] = {", name, len);
>                                                     ^
>   CC      mm/filemap.o
> In file included from /home/nekrad/src/apu2-dev/pkg/kernel.apu2.git/arch/x86/entry/vdso/vdso2c.c:166:0:
> /home/nekrad/src/apu2-dev/pkg/kernel.apu2.git/arch/x86/entry/vdso/vdso2c.h: In function 'extract32':
> /home/nekrad/src/apu2-dev/pkg/kernel.apu2.git/arch/x86/entry/vdso/vdso2c.h:38:52: warning: format '%lu' expects argument of type 'long unsigned int', but argument 4 has type 'size_t {aka unsigned int}' [-Wformat=]
>   fprintf(outfile, "static const unsigned char %s[%lu] = {", name, len);
>
> Signed-off-by: Enrico Weigelt, metux IT consult <info@...ux.net>
> ---
>  arch/x86/entry/vdso/vdso2c.h | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/entry/vdso/vdso2c.h b/arch/x86/entry/vdso/vdso2c.h
> index 1c7cfac7e64a..5c6a4bbc63f9 100644
> --- a/arch/x86/entry/vdso/vdso2c.h
> +++ b/arch/x86/entry/vdso/vdso2c.h
> @@ -35,7 +35,8 @@ static void BITSFUNC(extract)(const unsigned char *data, size_t data_len,
>         if (offset + len > data_len)
>                 fail("section to extract overruns input data");
>
> -       fprintf(outfile, "static const unsigned char %s[%lu] = {", name, len);
> +       fprintf(outfile, "static const unsigned char %s[%lu] = {", name,
> +               (unsigned long)len);

This would be nicer if you put the line break after the equal sign and
before the {.

--Andy